The paper-sheet feeding device used for a banknote counter or the like is configured for successively feeding the paper-sheets (e.g., banknotes or the like) stacked therein, one by one, so as to carry them to the outside.
Typically, in such a paper-sheet feeding device as described above, a feed roller and a thickness adjustment member are provided to a feeding unit for the paper-sheets, with a gap corresponding to thickness of one paper-sheet. Thus, the paper-sheet fed into the feeding unit can be fed out therefrom, one by one, while being controlled upon passing through the gap between the feed roller and the thickness adjustment member. However, in such a paper-sheet feeding device, when the paper-sheets are inserted and stuck between the feed roller and the thickness adjustment member, while being overlapped in two sheets or more, the feed roller will be in a locked state, and rotation of the feed roller will be stopped. In such a case, it will take unduly time and labor to remove such stuck paper-sheets.
To solve this problem, the paper-sheet feeding device as disclosed in JP5-8878A has been proposed. Now, such a conventional paper-sheet feeding device is described, with reference to FIGS. 4 and 5. FIG. 4 is a side view schematically showing construction of the conventional paper-sheet feeding device, and FIG. 5 is a diagram for schematically illustrating a state when the paper-sheet is fed out from the paper-sheet feeding device shown in FIG. 4. In FIG. 5, FIG. 5(a) is a schematic view showing a state before the paper-sheet is fed out, FIG. 5(b) is a schematic view showing a state when one paper-sheet is fed to a nip part between the feed roller and a pressure roller, and FIG. 5(c) is a schematic view illustrating a state when two paper-sheets are fed to the nip part between the feed roller and the pressure roller, while being overlapped with each other.
As shown in FIG. 4, the conventional paper-sheet feeding device includes a storing unit 90 configured for storing therein the plurality of paper-sheets P in a stacked condition, a kicker roller 80 provided to a bottom portion of the storing unit 90 and adapted for kicking the paper-sheets P stored in the storing unit 90, to the outside, one by one, and the feed roller 60 and pressure roller 70, each adapted for feeding out the paper-sheet P kicked out from the storing unit 90 by the kicker roller 80. The feed roller 60 is provided to be in contact with and pressed against the pressure roller 70, while the nip part N is formed between the feed roller 60 and the pressure roller 70.
The feed roller 60, as shown in FIG. 4, is configured to be continuously rotated, in a direction designated by an arrow as depicted in FIG. 4, upon performing a feed-out operation for the paper-sheet P. The feed roller 60 includes a base part 62 having a substantially disk-like shape and formed from, for example, a plastic or metal. The base part 62 has a rubber (not shown) provided around the whole outer circumference thereof. Along an axis of the feed roller 60, a feed roller shaft 61 for pivoting the feed roller 60 is provided to extend in a vertical direction relative to the sheet of FIG. 4. This feed roller 60 can serve to feed out each paper-sheet P kicked out by the kicker roller 80, while being in contact with a surface thereof.
The pressure roller 70, as shown in FIG. 4, includes a base part 72 having a substantially disk-like shape and formed from, for example, a suitable plastic or metal. Further, the base part 72 has another rubber (not shown) provided around the whole outer circumference thereof. Along the axis of the pressure roller 70, a pressure roller shaft 71 for pivoting the pressure roller 70 is provided to extend in the vertical direction relative to the sheet of FIG. 4. The nip part N is formed between the rubber provided around the base part 72 of the pressure roller 70 and the rubber provided around the base part 62 of the feed roller 60. Additionally, a torque limiter 73 is provided between the base part 72 of the pressure roller 70 and the pressure roller shaft 71. The torque limiter 73 is provided to allow the pressure roller 70 to be rotated, in a circumferential direction thereof (specifically, in a feed-out direction of the paper-sheet P), relative to the pressure roller shaft 71, when torque greater than a predetermined torque is applied to the pressure roller 70 along the circumferential direction thereof. Meanwhile, this torque limiter 73 interlocks the pressure roller 70 with the pressure roller shaft 71, when the torque that is less than the predetermined torque is applied to the pressure roller 70 along the circumferential direction thereof.
Furthermore, a pressure roller shaft drive transmission mechanism (not shown) adapted for driving the pressure roller shaft 71 to be continuously rotated is provided to the pressure roller shaft 71. Specifically, this pressure roller shaft drive transmission mechanism is provided to rotate the pressure roller shaft 71, at any time, at a low speed, in a direction reverse to the feed-out direction of the paper-sheet P, i.e., in the direction designated by another arrow as depicted in FIG. 4. Thus, the pressure roller 70 will be rotated in the feed-out direction of the paper-sheet P, against the rotation of the pressure roller shaft 71, when the torque applied to the pressure roller 70 in the circumferential direction thereof is greater than the predetermined torque, due to friction against the feed roller 60 or the like (see FIG. 4). Meanwhile, the pressure roller 70 will be interlocked with the pressure roller shaft 71 and rotated in the direction reverse to the feed-out direction of the paper-sheet P, when the torque applied to the pressure roller 70 in the circumferential direction thereof is less than the predetermined torque.
Next, the feed-out operation for the paper-sheet P, at the nip part N in such a conventional paper-sheet feeding device as shown in FIG. 4, will be described in more detail, with reference to FIG. 5. It is noted that the feed-out direction of the paper-sheet P is a right direction in FIG. 5.
FIG. 5(a) is a diagram schematically showing one exemplary state in which no paper-sheet P is fed to the nip part N between the feed roller 60 and the pressure roller 70. In this state, the feed roller 60 is continuously rotated in the feed-out direction of the paper-sheet P. Since the feed roller 60 is pressed against the pressure roller 70, a torque for driving the pressure roller 70 to be rotated together with the feed roller 60 is transmitted to the pressure roller 70 from the feed roller 60. This torque that is applied to rotate the pressure roller 70 (i.e., the torque applied to the pressure roller 70 in the circumferential direction thereof) is set greater than the predetermined torque set in the torque limiter 73. Therefore, the rotation of the pressure roller 70, relative to the pressure roller shaft 71, in the feed-out direction of the paper-sheet P, is allowed. Thus, as shown in FIG. 5(a), the pressure roller 70 will be rotated together with the feed roller 60, against the rotation of the pressure roller shaft 71.
Thereafter, as shown in FIG. 5(b), when one paper-sheet P is fed to the nip part N between the feed roller 60 and the pressure roller 70, frictional torque exerted between the rubber provided around the outer circumference of the base part 62 of the feed roller 60 and the paper-sheet P as well as exerted between the rubber provided around the outer circumference of the pressure roller 70 and the paper-sheet P. At this time, both the frictional torque generated between the rubber of the feed roller 60 and the paper-sheet P and the frictional torque generated between the rubber of the pressure roller 70 and the paper-sheet P, at the nip part N, are greater than the predetermined torque applied from the torque limiter 73. Therefore, also in this case, the rotation of the pressure roller 70, relative to the pressure roller shaft 71, in the feed-out direction of the paper-sheet P, is allowed. Thus, as shown in FIG. 5(b), the pressure roller 70 will be rotated together with the feed roller 60, against the rotation of the pressure roller shaft 71.
However, if two paper-sheets P are accidentally kicked out by the kicker roller 80, while being overlapped with each other, such two overlapped paper-sheets P will be fed to the nip part N between the feed roller 60 and the pressure roller 70, as shown in FIG. 5(c). In such a case, the frictional torque is exerted between the rubber of the feed roller 60 and one of the two paper-sheets P as well as exerted between the rubber of the pressure roller 70 and the other of the paper-sheets P. Furthermore, the frictional torque is also exerted between such a pair of overlapped paper-sheets P. Namely, when such two overlapped paper-sheets P are fed to the nip part N, the torque applied to the pressure roller 70 in the circumferential direction thereof will be the frictional torque exerted between the pair of paper-sheets P. However, such frictional torque exerted between the pair of paper-sheets P is significantly less than the predetermined torque set in the torque limiter 73. Therefore, the rotation of the pressure roller 70 in the feed-out direction of the paper-sheet P, relative to the pressure roller shaft 71, will not be allowed by the torque limiter 73 and the pressure roller 70 will be interlocked with the pressure roller shaft 71. In other words, the pressure roller 70 will be rotated in the direction reverse to the feed-out direction of the paper-sheet P. Consequently, the one of the two overlapped paper-sheets P, on the side of the feed roller 60, will be fed out from the nip part N, in the right direction in FIG. 5, while being moved together with the rotation of the feed roller 60. Meanwhile, the other of the two overlapped paper-sheets P, on the side of the pressure roller 70, will not be fed out from the nip part N, due to the rotation of the pressure roller 70 in the direction reverse to the feed-out direction of the paper-sheet P.
However, there are various problems still remaining in such a conventional paper-sheet feeding device. First, it is necessary to provide the pressure roller shaft drive transmission mechanism, in order to drive the pressure roller shaft to be continuously rotated. Therefore, the construction of the paper-sheet feeding device becomes considerably complicated, thus increasing the production cost. Secondly, as shown in FIG. 5, even in the case except that two or more paper-sheets P are fed, accidentally, at a time, to the nip part N, i.e., even in the case in which the paper-sheets P are fed, normally, one by one, to the nip part N, slipping against the torque exerted from the torque limiter 73 always occurs between the pressure roller 70 and the pressure roller shaft 71. Therefore, in such a conventional paper-sheet feeding device, considerably high durability should be required for the torque limiter 73, thus rendering such a torque limiter 73 quite expensive.
Additionally, in the conventional paper-sheet feeding device, for example, when the two paper-sheets P are fed, accidentally, at a time, to the nip part N, after the paper-sheets P are fed, normally, one by one, to the nip part N, as shown in FIG. 5(b), the direction of rotation of the pressure roller 70 relative to the pressure roller shaft 71 will be changed from the feed-out direction into the direction reverse to the feed-out direction (i.e., a feed-in direction). Therefore, such a switching operation for the rotational direction of the pressure roller 70 takes additional time, making it difficult to achieve desired increase of the feed-out speed of the paper-sheets P.